In the New Yorker article You have no idea what happened, Maria Konnikova convincingly explains how our memories are unreliable, particularly when paired with strong emotions. In a study which compared student memories of what they were doing at the time of the Challenger disaster captured at the time and again 30 months later, the two sets of memories bore little resemblance. The accuracy of recall typically scored just 3 on a 7 point scale, but students were highly confident that their memories were accurate.
Another study that looked at the correlation between emotion and accuracy of remembered detail found a substantially negative correlation:
… each scene was presented within a frame, and, from scene to scene, the color of the frames would change. When it came to the emotional images, memory of color ended up being significantly worse than memory of neutral scenes. Absent the pull of a central, important event, the students took in more peripheral details. When aroused, they blocked the minor details out. (emphasis added)
Konnikova concludes that when it comes to memory, we must “err on the side of caution: unless we are talking about the most central part of the recollection, assume that our confidence is misplaced”.
But it’s worth remembering that the reason we know what students were really experiencing on the day of the Challenger disaster is because records were kept at the the time of the event. Unlike memory, written records don’t degrade, get overwritten or get affected by our subsequent experiences.
As an objective, nonvolatile assessment of the world, records can correct our judgement of past events. People often think of records as ‘just overhead’, or only for the benefit or some hypothetical future coworker. But in fact routine recordkeeping is an important discipline for anyone who wants to be guided by the truth rather than their unreliable memories.